Transport minister Keiichi Ishii on Tuesday ordered Tokyo Metro to investigate an incident Monday in which an empty baby stroller was dragged 100 meters along a platform after becoming stuck in train doors.
Tokyo Metro President Yoshimitsu Oku, who met with Ishii later in the day, apologized for the incident.
"We apologize for causing worry among our passengers," Oku said.
Oku said the company will conduct training on the use of emergency brakes and continue to set up safety barriers on platforms.
According to the subway operator, the stroller became wedged in the doors at about 3 p.m. Monday at Kudanshita Station on the Hanzomon Line.
It said a mother holding her baby entered the train first, followed by the father, who was pushing the empty stroller. However, when the father tried to get on board, the doors closed and one of the wheels got stuck.
Since the clearance was less than 15 mm and undetectable for the door sensor, the train started to run without any alarm activating, the operator said.
Efforts by passengers who pushed the emergency stop button also did not work. After about 100 meters, the stroller hit the railings at the end of the platform.
The conductor of the train, who is in her 20s, reportedly said she gave priority to subway operations and failed to stop the train immediately.
Ishii said Tuesday that he had instructed Tokyo Metro to investigate exactly what happened and come up with measures to prevent a recurrence.
"It could have led to a large-scale accident and it's very regrettable," he told reporters.
Tokyo Metro said it will strengthen the education of its employees to ensure the safety of its operations.
